Marion climate

Marion Frost Dates and Growing Season

NOAA 1991-2020 normals for Monroe 26 N, 11.9 km from Marion, elevation 88 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Monroe 26 N. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

The last spring freeze typically comes around March 25 and the first fall freeze around November 5, a growing season of about 226 days.

Median at 36°F
last April 7, first October 25
Median at 32°F
last March 25, first November 5
Median at 28°F
last March 9, first November 18

Last freeze in spring

The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.

Threshold10%20%30%40%50%60%70%80%90%
36°FApr 24Apr 18Apr 15Apr 11Apr 7Apr 4Mar 31Mar 26Mar 18
32°FApr 10Apr 5Apr 2Mar 29Mar 25Mar 20Mar 15Mar 10Mar 2
28°FMar 30Mar 22Mar 16Mar 12Mar 9Mar 4Feb 28Feb 23Feb 15
24°FMar 14Mar 7Mar 2Feb 27Feb 22Feb 15Feb 7Jan 31Jan 23
20°FMar 3Feb 22Feb 14Feb 6Jan 31Jan 28Jan 21Jan 11Dec 31
16°FFeb 17Feb 5Feb 1Jan 27Jan 22Jan 15Jan 9Jan 3Dec 25

First freeze in fall

The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.

Threshold10%20%30%40%50%60%70%80%90%
36°FOct 11Oct 16Oct 20Oct 23Oct 25Oct 29Nov 1Nov 3Nov 8
32°FOct 20Oct 25Oct 30Nov 2Nov 5Nov 8Nov 11Nov 17Nov 23
28°FOct 31Nov 5Nov 9Nov 13Nov 18Nov 22Nov 26Dec 1Dec 7
24°FNov 11Nov 19Nov 26Dec 1Dec 4Dec 8Dec 18Dec 30Jan 5
20°FNov 30Dec 6Dec 16Dec 23Dec 30Jan 4Jan 9Jan 18Feb 1
16°FDec 12Dec 22Dec 30Jan 3Jan 7Jan 12Jan 19Jan 31Feb 5

Growing season length

Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.

Threshold10%20%30%40%50%60%70%80%90%
36°F226217212206202198193187180
32°F252243237231226221214209200
28°F286274266261255250245238226
24°F329316307299293285276267255
20°F365355344337329321314305292
16°F365365365365365358347337326

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder
100% of years
32°F or colder
100% of years
28°F or colder
100% of years
24°F or colder
100% of years
20°F or colder
89% of years
16°F or colder
51% of years

Degree days

A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.

Heating degree days, base 65°F
2,627
Cooling degree days, base 65°F
2,080
Growing degree days, base 40°F
8,707
Growing degree days, base 45°F
7,087
Growing degree days, base 50°F
5,604
Growing degree days, base 55°F
4,264
Growing degree days, base 60°F
3,085

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January634264
February478690
March30619223
April11760398
May21212656
June0396846
July0502967
August0480945
September6300744
October13084424
November36514167
December570482

What this means

NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.

The station is 11.9 km from Marion. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USW00053961 (Monroe 26 N). Public domain.